JPH0626382A - Electronic type injector for otto engine - Google Patents

Abstract

PURPOSE: To provide an injection system capable of assuring optimal measurement and dosaging of a mass flow of air at minimum structural expense and within a minimum space, particularly in the case of rapidly varying engine loads and speeds of rotation of an engine. CONSTITUTION: An injection system comprises a convergent/divergent nozzle 12 with a narrowest cross section adjustable by a throttle body 14; a position indicator 18 for the nozzle body 14; measurement devices for measuring a pressure po in front of the nozzle 12 and a pressure pL at the narrowest point of the nozzle 12 and an air temperature To in front of the nozzle 12; and an electronic controller device 19 operative with at least the input variables of the above-mentioned po pL, To and a position of the nozzle body to provide an output variable of opening time to of the injection nozzle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic injection device for an otto engine, which is provided with an injection nozzle, an adjustable throttle body arranged in the intake air flow, and an air mass flow measuring device. It is related to the format.

[0002]

In electronically controlled gasoline injectors, the air characteristic lambda is pre-controlled by adding a fuel mass flow rate which corresponds to the air mass flow rate. The closer the pre-control of the air characteristics is to the value of Lambda = 1, the less the Lambdasonde's regulating action is, and the narrower the "Lambda window" needed to optimally convert the harmful substances in the exhaust gas. it can. This is especially true for rapidly changing engine loads and engine speeds.

In electronic injectors known in the field, the intake flow is usually regulated by means of a throttle valve. To meter the fuel, the air mass flow rate is detected using a measuring mechanism such as a damming disc or a hot wire sonde. Therefore, the control of the air mass flow rate and the detection of the air mass flow rate are performed via separate members, which means that not only many members are required but also the response sensitivity becomes low. Means This is because, in this case, the adjustment of the fuel mass flow can only be carried out after the air mass has been measured. In addition to these fundamental drawbacks, the detection of air mass flow rates using damming discs has the drawbacks of high inertia, large built-in volume and high manufacturing costs. It is difficult to measure the air mass flow rate by the hot wire / air flow rate measuring device due to the pulsation of the air flow caused by the intake operation of the air-fuel mixture performed through the cylinder. In addition to this, a resonance phenomenon that can only be partially compensated for by engine-specific modifications,
There is also a drawback that it occurs at a certain specified number of revolutions.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is therefore to improve an injector of the type mentioned at the outset such that it requires a minimum of production costs and space requirements, and that engine load changes particularly rapidly. Another object of the present invention is to provide an injection device capable of reliably and optimally adjusting and measuring the air mass flow rate even at the engine speed.

[0005]

In order to solve this problem, the structure of the present invention is provided with a convergent / diffusion type nozzle whose narrowest cross section can be adjusted by the diaphragm body. Position display mounting, pressure p ₀ in front of the nozzle, pressure p in the narrowest part of the nozzle
_L and a measuring mechanism for measuring the air temperature T _{0 in} front of the nozzle, at least the input value p
An electronic control unit is provided which receives ₀ , p _L , T ₀ and the position of the nozzle body and outputs the opening time toe of the injection nozzle as an output value.

[0006]

Based on the configuration of the electronic injection device according to the present invention, the throttle body is directly or indirectly provided with the air mass control function and the air mass measurement function.
The functioning of electronic injectors is based exclusively on physical qualities, not on the expensive engine characteristic range to be accepted. This means that the air mass flow rate is the above-mentioned values p ₀ , p _L , T in the case of static isentropic flow.
₀ and the recognition that it is defined by the narrowest cross-section of the nozzle, which is reproducible by the throttle body position, and on the basis that the flow velocity of the intake air corresponds to the speed of sound over the wide operating range of the engine. Pressure p _L is "critical value"
Below, there is no change in the air condition and flow velocity in the narrowest cross section of the nozzle. This means that the mass air flow is constant when the position of the throttling mechanism does not change. When the engine load rises from the "critical flow state" in the narrowest cross section of the nozzle and exceeds the specified air pressure p _L , the "critical flow" of "sonic velocity" becomes "subcritical" of "subsonic velocity". Flow of ". If the throttle mechanism remains in the same position, this reduces the mass air flow drawn by the engine.

On the basis of what has been stated above, it is sufficient to detect the values p ₀ , p _L , T ₀ and the position of the throttle body in order to measure the mass air flow. These values are sent to an electronic control unit which converts the values into an output value of the opening time toe of the injection nozzle, the opening time being caused by the injection characteristics of the injection nozzle. Of course, instead of one injection nozzle, a plurality of injection nozzles, in particular a number corresponding to the number of cylinders, may be provided. In this case, the fuel mass flow rate of the injection nozzle can be set in relation to the opening time of the injection nozzle. The invention is not limited to the input of said physical values into an electronic control unit, but other purposeful input values, such as engine speed, actively detected lambda values. It is also possible to make properties such as idling, warm-up, and acceleration act on the opening time toe via the electronic control unit.

In a preferred embodiment of the invention, a rigid adjusting element is connected to the throttle body, to which the pedal cable of the accelerator pedal is kinematically connected. Furthermore, it is also possible to adjust the diaphragm body or the adjusting element by means of a servomotor which is electrically controlled by an accelerator pedal. The movement of the diaphragm body is advantageously indicated by a slider associated with the adjusting element and cooperating with the potentiometer of the position indicator. The position of the diaphragm body can also be defined by means of other suitable elements.

A further advantageous wooden housing according to the invention is that the diaphragm body is designed as a diaphragm plate and the diffuser of the nozzle is designed as a radial diffuser. With such a configuration, throttling and measurement of the air mass flow can be realized at a small structural height of the associated member. It is likewise advantageous in such an arrangement for the radial diffuser to be surrounded by an air filter. With this configuration, the intake air is filtered by the filter and then flows into the inner radial diffuser and flows out toward the outside. In a further configuration of the invention, the throttle body is configured as a throttle cone and the diffuser of the nozzle is straight.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows an Otto engine 1 having an intake pipe 2, an exhaust pipe 3, an injection nozzle 4 and an ignition distributor 5. The electro fuel pump 6 pumps fuel from the fuel tank 7 through the fuel filter 8 to the injection nozzle 4. The fuel pressure regulator 9 cooperates with the injection nozzle 4 and is connected to the fuel tank 7 and the intake pipe 2. Electrical energy is introduced into the system via the generator 10 and the ignition / start switch is shown at 11.

The intake air is supplied to the intake pipe 2 through a convergent / diffusion type nozzle 12 having a straight diffuser 13, and inside the nozzle 12, a throttle body 14 in the shape of a throttle cone is formed in the longitudinal direction. It is shiftably mounted so that the narrowest cross section of the nozzle 12 can be adjusted. On the inflow side, symmetrically with respect to the throttle body 14,
A rigid adjusting element 15 is rigidly connected to the throttle body, which is axially slidably mounted in a bearing 16 and is kinematically connected to an accelerator pedal (not shown). There is. A slider 17 is associated with the adjusting element 15 and cooperates with the potentiometer of the adjusting and damping device 18.

The electro fuel pump 6, the injection nozzle 4,
The ignition distributor 5 and the lambda sonde 20 inserted in the exhaust pipe 3 are electrically connected to an electronic control unit 19 which controls and regulates the electronic injection device. The air temperature T ₀ and the pressure p ₀ in front of the nozzle and the pressure p _{L at} the narrowest point of the nozzle are also detected via a suitable measuring mechanism. Values p _L , p ₀ , T
₀ and diaphragm body 1 verified by potentiometer
The position x of 4 is electrically supplied to the electronic control unit 19 as an input signal. On the basis of the physical laws already mentioned, the electronic control unit 19 calculates the air mass flow rate from the above-mentioned values, and further, regarding the injection nozzle 4 for injecting fuel, the opening time toe of the injection nozzle is set to the optimum mixture composition. Calculate to get.

FIG. 2 shows the givenness in the region of the throttle body 14 designed as a throttle cone, with the intake pipe 2 connected to a straight diffuser 13. FIG. 2 further shows input values and output values of the electronic control unit 19. In this case, the input values relating to the engine speed and the composition of the exhaust gas are also included, and further input values, such as values related to idling, warm-up and acceleration, are input via the electronic control unit. It can affect the opening time toe of the injection nozzle 4.

In the embodiment shown in FIG. 3, the end of the adjusting element 15 facing the intake pipe 2 receives a throttle body 14 which is embodied as a throttle plate, which throttle body comprises a nozzle. A convergent / diffusion type nozzle 12 is formed together with the main body 21. However, instead of opening into a straight diffuser, this nozzle opens into the radial diffuser 22. The adjusting element 15 then passes through the nozzle body opening 23, and the throttle body 14 associated with the adjusting element 15 forms with the nozzle body 21 a radial diffuser 22.
The convergent / diffusion type nozzle 12 has a normal air filter 25 which is arranged in an air filter casing 24 and has a flat configuration.
In the radial direction, it passes through the air filter 25 and the nozzle 12 into the intake pipe 2, where it is throttled by more or less throttle body 14 in relation to the position of the throttle body 14. Behind the air filter 25 and in front of the nozzle 12,
The values T ₀ and p ₀ are detected.

In FIG. 4, the pressure p _{L at the} narrowest point of the nozzle 12 and the air mass flow m _a ′ − flowing through the nozzle, which are the basis of the function of the electronic injection device described above, are shown.
The relationship between and is shown. The diagram in FIG. 4 is based on the detection of the air mass flow rate in a static isentropic flow, assuming that p ₀ and T ₀ are constant except p _L. When the pressure of the air in the intake pipe is below the "critical value", based on the recognition that the flow velocity of the air taken in at the narrowest cross section of the nozzle for a wide operating range of the engine corresponds to the speed of sound. Means that there is no change in the flow velocity and air conditions in the narrowest cross section of the nozzle. As a result, the air mass flow rate is constant when the position of the throttle body does not change.
"Critical flow conditions" in the narrowest cross section of the nozzle
When the load of the engine rises from the above to exceed the specified air pressure p _L , the transition to the subcritical flow occurs. This reduces the mass flow of air drawn in by the engine if the position of the throttle body remains unchanged. Value p _L , p
By using ₀ and T ₀ and by detecting the air mass flow rate by means of the travel distance detection x of the throttle body, it is possible to indicate the opening time toe of the injection nozzle for optimal precontrol of the air characteristics. The closer this pre-control of the air properties is to Lambda = 1, the less the regulating action of the Lambda sonde on the electronic control unit 19 may be, whereby the fine "Lambda Lambda" necessary for optimal conversion of the exhaust gas harmful substances. Windows.

[Brief description of drawings]

1 is a schematic view of an electronic injection device according to the invention in which the throttle body according to the first embodiment is arranged in the intake flow.

2 shows the configuration of the throttle body shown in FIG. 1 with the associated nozzle body and the input and output values for the intake mass flow rate.

FIG. 3 is a view corresponding to FIG. 2 and showing another embodiment of the nozzle body.

FIG. 4 is a diagram showing a relationship between pressure and air mass flow rate in a convergent / diffusion type nozzle formed between a throttle body and a nozzle body.

[Explanation of symbols]

1 Ot engine, 2 intake pipes, 3 exhaust pipes, 4
Injection nozzle, 5 ignition distributor, 6 electro fuel pump, 7 fuel tank, 8 fuel filter, 9 fuel pressure regulator, 10 generator, 11 ignition / start switch, 12 convergence / diffusion nozzle,
13 straight diffuser, 14 diaphragm body,
15 adjustment elements, 16 bearings, 17 sliders, 18 position display devices, 19 electronic control devices,
20 Lambda Sonde, 21 Nozzle Body, 22 Radial Diffuser, 23 Nozzle Body Opening, 24
Air filter casing, 25 air filter

Claims (7)

[Claims] 1. An electronic injection device for an Otto engine, of the type provided with an injection nozzle, an adjustable throttle body arranged in the intake flow and an air mass flow measuring device. At the narrowest cross-section at the body (14)
Adjustable and convergent / diffusion nozzle (12)
Is provided, the position indicator (18) for the nozzle body (14) and the pressure p in front of the nozzle (12).
_O , a pressure p _L in the narrowest part of the nozzle (12) and a measuring mechanism for measuring the air temperature T _{O in} front of the nozzle (12) are provided, at least the input values p _O , p _L. , T _o and the position (x) of the nozzle body and an electronic control unit (19) for outputting the opening time toe of the injection nozzle as an output value is provided. Injection device. 2. The injection device according to claim 1, wherein the electronic control unit (19) further receives, as other input values, the rotational speed n of the Otto engine and the air characteristic lambda. 3. A rigid adjusting element (15) is connected to the throttle body (14), said adjusting element comprising:
3. The injection device according to claim 1, wherein the pedal cable of the accelerator pedal is kinematically connected. 4. The injection device according to claim 3, wherein the slider (17) associated with the adjusting element (15) cooperates with the potentiometer of the position indicator (18). 5. The diffuser (13) of the nozzle (12), wherein the throttle body (14) is constructed as a throttle cone.
The injection device according to any one of claims 1 to 4, wherein the injection device is configured straight. 6. The diaphragm body according to claim 1, wherein the throttle body (14) is designed as a diaphragm plate and the diffuser of the nozzle (12) is designed as a radial diffuser (22). Injection device. 7. The radial diffuser (22) is surrounded by an air filter (25).
The injection device described.